Synchronized channel access in coexisting wireless networks

ABSTRACT

A system and method for arbitrating channel access in a wireless device including co-located network transceivers are disclosed herein. A wireless device includes a first wireless transceiver and a second wireless transceiver. The first transceiver is configured for operation with a first wireless network. The second transceiver is configured for operation with a second wireless network. The wireless device further includes logic that determines which of the first and second transceivers is enabled to transmit at a given time. The logic causes the first transceiver to transmit a notification signal indicating a time period during which the second transceiver of the wireless device will perform a first wireless transaction, and during which, based on receiving the notification signal, a different wireless device performs a second wireless transaction via the second wireless network without transmitting a notification signal.

CROSS-REFERENCE TO RELATED APPLICATIONS

This application is divisional of application Ser. No. 12/559,853 filedSep. 15, 2009 (now granted as U.S. Pat. No. 8,537,803 issued on Sep. 17,2013) which is a non-provisional application claiming priority toprovisional application Ser. No. 61/097,056, filed on Sep. 15, 2008,entitled “Channel Utilization Via Bluetooth Activities SynchronizationIn Coexisting Wireless Networks,” the teachings of which areincorporated by reference herein.

BACKGROUND

As wireless technologies proliferate, mobile wireless devicesincorporate a multiplicity of different wireless standards. For example,a cellular telephone can accommodate a cellular network (e.g., UniversalMobile Telecommunications System), a wireless local area network(“WLAN”), such as IEEE 802.11, and a wireless personal area network(“WPAN”) (e.g., Bluetooth). Including WPAN access makes utilization of awireless device more convenient by allowing use of wireless headsets andother short-range wireless appliances.

Some of the various wireless standards adopted for use in mobile devicesuse adjacent and/or overlapping portions of the wireless spectrum. Forexample, both Bluetooth and IEEE 802.11 b/g/n occupy the 2.45 GHz band.

SUMMARY

A system and method for arbitrating channel access in a wireless deviceincluding co-located network transceivers is disclosed here. In someembodiments, a wireless device includes a first wireless transceiver anda second wireless transceiver. The first transceiver is configured foroperation with a first wireless network. The second transceiver isconfigured for operation with a second wireless network. The wirelessdevice further includes logic that determines which of the first andsecond transceivers is enabled to transmit at a given time. The logiccauses the first transceiver to transmit a notification signalindicating a time period during which the second transceiver of thewireless device will perform a first wireless transaction, and duringwhich, based on receiving the notification signal, a different wirelessdevice performs a second wireless transaction via the second wirelessnetwork without transmitting a notification signal.

In accordance with at least some other embodiments, a method includesreceiving, by a first wireless device via a first transceiver configuredfor operation on a first wireless network, a notification signaltransmitted on the first network by a second wireless device. Thenotification signal indicates a time period during which the secondwireless device will perform a wireless transaction on a second wirelessnetwork. A second transceiver of the first wireless device is enabled,based on receipt of the notification signal, to perform a differentwireless transaction on the second wireless network during the timeperiod specified in the received notification signal. The first wirelessdevice performs the different wireless transaction absent acorresponding notification signal transmission by the first wirelessdevice.

In accordance with yet other embodiments, a wireless device includes afirst wireless transceiver, a second wireless transceiver, and anarbiter. The first wireless transceiver is configured for communicationvia a first wireless network. The second wireless transceiver isconfigured for communication via a second wireless network. The arbitercontrols which of the first and second transceivers is enabled totransmit at a given time. The arbiter schedules wireless transactionsvia the second transceiver based on timing signals wirelessly receivedvia the first transceiver.

In accordance with further embodiments, a wireless device includes afirst wireless transceiver, a second wireless transceiver, andsynchronization logic. The first transceiver is configured for operationwith a first wireless network. The second transceiver is configured foroperation with a second wireless network. The synchronization logicreceives a timing signal transmitted via the first wireless network andsynchronizes transactions via the second transceiver to the timingsignal.

In accordance with additional embodiments, a method includes receiving,by a first wireless device via a first transceiver configured foroperation on a first wireless network, a timing signal transmitted onthe first network. A second transceiver of the first wireless deviceconfigured for operation on a second wireless network is synchronized tothe received timing signal.

BRIEF DESCRIPTION OF THE DRAWINGS

For a detailed description of exemplary embodiments of the invention,reference will now be made to the accompanying drawings in which:

FIG. 1 shows a wireless system including wireless devices that use twointerfering wireless networks in accordance with various embodiments;

FIG. 2 shows a diagram of signals transmitted in a wireless systemincluding network arbitration based on channel accesscontrol/notification signals in accordance with various embodiments;

FIG. 3 shows a block diagram of a wireless device including networkarbitration that synchronizes activities on the second transceiver basedon timing signals received from the first transceiver and that controlstransmission based on channel access notification signals in accordancewith various embodiments; and

FIG. 4 shows a flow diagram for a method of network arbitration thatsynchronizes activities on the second transceiver based on timingsignals received from the first transceiver and that controlstransmission based on channel access notification signals in accordancewith various embodiments.

NOTATION AND NOMENCLATURE

Certain terms are used throughout the following description and claimsto refer to particular system components. As one skilled in the art willappreciate, companies may refer to a component by different names. Thisdocument does not intend to distinguish between components that differin name but not function. In the following discussion and in the claims,the terms “including” and “comprising” are used in an open-endedfashion, and thus should be interpreted to mean “including, but notlimited to . . . ” Also, the term “couple” or “couples” is intended tomean either an indirect or direct electrical connection. Thus, if afirst device couples to a second device, that connection may be througha direct electrical connection, or through an indirect electricalconnection via other devices and connections. Further, the term“software” includes any executable code capable of running on aprocessor, regardless of the media used to store the software. Thus,code stored in memory (e.g., non-volatile memory), and sometimesreferred to as “embedded firmware,” is included within the definition ofsoftware.

DETAILED DESCRIPTION

The following discussion is directed to various embodiments of theinvention. Although one or more of these embodiments may be preferred,the embodiments disclosed should not be interpreted, or otherwise used,as limiting the scope of the disclosure, including the claims. Inaddition, one skilled in the art will understand that the followingdescription has broad application, and the discussion of any embodimentis meant only to be exemplary of that embodiment, and not intended tointimate that the scope of the disclosure, including the claims, islimited to that embodiment.

Disclosed herein are a system and method for scheduling access to awireless transmission channel in a system that includes wireless devicesusing multiple conflicting wireless networks. Mobile wireless devicesare sometimes capable of accessing multiple exclusive wireless networks.Such wireless networks can occupy adjacent or overlapping frequencyspectrum. For example, Bluetooth and IEEE 802.11b/g/n both utilize the2.4-2.5 GHz band. Access to the networks can be coordinated via timemultiplexing to reduce performance degradation caused by collisions thatmay occur when the networks are simultaneously accessed. Networkperformance degradation can also result when a mobile device istransmitting via a first network (e.g., Bluetooth) when another networkdevice transmits a packet to the mobile device via a second network(e.g., a WLAN). The mobile device will be unable to transmit anacknowledge signal because channel access is reserved for transmissionvia the first network. Consequently, the device transmitting via thesecond network may conclude that the packet was lost and reduce thetransmission rate of subsequent packets. The longer transmissioninterval resulting from the reduced rate may further increase the numberof collisions with transmissions via the first network at the mobiledevice, ultimately resulting in progressive performance degradation(i.e., an avalanche effect).

One method avoiding such progressive deterioration of performanceinvolves transmission of a signal notifying network devices that theyare not allowed to transmit during a duration specified by the signal.For example, in a system included devices having co-located Bluetoothand WLAN transceivers, a device planning a Bluetooth transmission maytransmit a notification signal (e.g., a CTS2SELF frame) via the WLAN toinform other WLAN devices to avoid any transmission during the upcomingBluetooth transmission. CTS2SELF is a self-addressed packet containing aduration field specifying transceiver is configured to performtransactions (e.g., transmit or receive) via the second transceiver insynchronization with a second transceiver of a different wireless devicea time duration during which WLAN devices other than the transmittingdevice are not allowed to transmit any packets. WLAN devices receivingthe CTS2SELF packet inhibit WLAN transmissions in accordance with theduration field. Unfortunately, the time available for WLAN access may bereduced in correspondence to the number of devices in a wireless networkusing such a notification method.

Notification signaling, as described above may not be wholly effectiveat preventing progressing performance degradation. If a first mobiledevice transmits a notification signal, a second mobile device wishingto transmit a notification signal during the WLAN exclusion intervalwill be unable to do so. If the second device thereafter transmits viaBluetooth, the transmission will be unprotected, and another wirelessdevice may transmit a packet via WLAN to the second device during theBluetooth transmission resulting in the progressive performancedegradation (avalanche effect) described above.

Embodiments of the present disclosure employ a distributed schedulingalgorithm to alleviate progressive performance degradation in networksutilizing devices having co-located network transceivers configured foroperation in wireless networks that may interfere with one another.

FIG. 1 shows an embodiment of a wireless system including wirelessdevices configured to use two different wireless networks that mayinterfere with one another when simultaneously accessed. The wirelesssystem 100 includes an access point 102, wireless devices 104 and 106,and wireless devices 108 and 110. The access point 102, and the wirelessdevices 104, 106 each include a wireless transceiver 112. The wirelesstransceiver 112 allows the access point 102 and the wireless devices104, 106 to communicate via a first wireless network, for example, aWLAN (e.g., IEEE 802.11 b/g/n). The wireless devices 104, 106 also eachinclude a second wireless transceiver 114. The second wirelesstransceiver 114 allows the wireless devices 104, 106 to communicate viaa second wireless network, for example, a WPAN (e.g., Bluetooth). Thewireless devices 108, 110 each include a transceiver 114 forcommunicating via the second wireless network. In practice, the system100 may include any number of wireless devices 104, 106, 108, 110.Exemplary mobile wireless devices 104, 106 include cellular telephones,personal digital assistants, personal computers, navigation devices,personal music players, video gaming systems, etc. Exemplary mobilewireless devices 108, 110 include wireless headsets, wireless earphones,etc.

The access point 102 can also be referred to as a base station, a nodeB, etc. The access point 102 may connect the wireless devices 104, 106to a wired network, serve as an intermediary for communication betweenthe wireless devices 104, 106, and/or provide other networking services(e.g., timing services) to the wireless devices 104, 106. Someembodiments of the system 100 can employ ad-hoc networking, and may notinclude the access point 102. Instead, in such embodiments, the mobilewireless devices 104, 106 can communicate directly with one another.

The first wireless network is incompatible with the second wirelessnetwork in that the wireless technologies and/or protocols used by thesecond network do not allow for wireless communications via the firstnetwork. The frequency bands used by the second network can be adjacentto or overlap the frequency bands used by the first network.Consequently, operation of the first network can interfere withoperation of the second network by directly interfering withtransmissions in overlapping bands or by out-of-band emissions thatsaturate receivers or interfere with transmissions in adjacent frequencybands.

To reduce interference between the first and second networks, thewireless devices 104, 106 may transmit a notification signal via thefirst network (using transceivers 112). The notification signal requiresother devices using the first network (e.g., access point 102, devices104, 106) to refrain from transmitting via the first network during thespecified in the notification signal (e.g., second network transmissioninterval).

As explained above, some embodiments of such a notification methods mayreduce access time available to the first network and/or leave the firstnetwork susceptible to progressive performance degradation. Embodimentsof the present disclosure employ a distributed scheduling algorithm thatmakes use of the aforementioned notification signaling while improvingfirst network access time and reducing the likelihood of performancedegradation due to the avalanche effect. Embodiments of the wirelessdevices 104, 106 synchronize activities on the second wireless networksuch that a single notification signal transmitted by either of thewireless devices 104, 106 can provide protection for both devices 104,106. Configuring the wireless devices 104, 106 to access the secondnetwork based on a notification signal transmitted by any other wirelessdevice 104, 106 in the first network reduces the number of notificationsignals transmitted via the first network. Moreover, second networktransmissions are protected by the exclusive channel access intervalprovided by the notification signal, thereby reducing the incidence ofavalanche effect.

FIG. 2 shows a diagram of signals transmitted in the wireless system 100including network arbitration based on channel access notificationsignals in accordance with various embodiments. The wireless device 104is ready to transmit data to the wireless device 108 via transceiver114. To gain exclusive access to the channel for transmission, thewireless device 104 transmits a notification signal 202 via thetransceiver 112 on the first network. The notification signal requiresthe access point 102 and the wireless device 106 to refrain fromtransmitting via transceivers 112 during a time period specified by thenotification signal 202.

The wireless device 104 transmits 204 via transceiver 114 at the timespecified via the notification signal 202. Moreover, the wireless device106 may also enable its transceiver 114 to transmit 206 during thespecified time interval. Thus, any second network transmissions fromwireless device 106 are protected by the notification signal 202transmitted by wireless device 104. The access point 102 refrains fromtransmitting 212 during the specified interval.

Notification signal transmissions by the wireless devices 104, 106 maybe randomized to reduce the likelihood of collisions. If one wirelessdevice (e.g., 106) receives a notification signal transmitted by anotherwireless device (e.g., 104) while a notification signal transmission ispending in the wireless device 106, then the wireless device 106discards the pending notification signal transmission and may transmitin the second network during the interval specified by the receivednotification signal.

Allowing multiple wireless devices 104, 106 to simultaneously transmitvia the second network may increase the possibility of collisions.However, if the second network employs a frequency hopping spreadspectrum technique (e.g., as in Bluetooth), the likelihood of collisionsis reduced. To further reduce the probability of collisions, someembodiments divide devices including co-located transceivers 112, 114into a plurality of groups. The devices in a group are synchronized andresponsive to notification signals transmitted by other devices in thegroup. By grouping devices in this manner, the number of devices in agroup is reduced thereby lessening the possibility of collision when thesecond network includes many devices.

Following the network 2 transmission interval 204, the access point 102and the wireless devices 104, 106 enable transmission via transceivers112 on the first network. The wireless devices 104, 106 may alsoschedule transmission of a notification signal for a random timefollowing the transmit interval 204. In FIG. 2, the notification signal208 is transmitted by the wireless device 106. The access point 102 andthe wireless device 104 receive the notification signal 208. Asexplained above, in response to the notification signal 208,transmissions on the first network are disabled and wireless devices104, 106 are enabled to transmit 210 on the second network during theinterval specified by the notification signal 208.

Embodiments of the wireless devices 104, 106 synchronize activitiesperformed via the second network. Synchronization may be achievedwithout any involvement of the wireless devices 108, 110. Someembodiments apply timing information provided via the first network tosynchronize activities on the second network. For example, an IEEE802.11 b/g/n access point 102 transmits special frames called beaconsthat contain a copy of the access point's Timing SynchronizationFunction (“TSF”). The TSF is used synchronize wireless devicesassociated (e.g., in a basic service set) with the access point 102.Using the TSF, the transceivers 112 of wireless devices 104, 106 areable to share the same clock.

Embodiments of the wireless devices 104, 106 employ the shared clock tosynchronize the activities of the second network. In some embodiments, aclock used by the transceiver 114 of the wireless devices 104, 106 issynchronized with the clock shared via the first network transceivers112. Certain second network transmissions (e.g., high priority perioddata transfers) may be scheduled to occur at predetermined intervals ofthe shared clock. For example, such transmissions may be scheduled formultiples of 3.75 milliseconds, which is the length of six Bluetoothslots, or other intervals as required for periodic traffic.

As explained above, transmission of notification signals (e.g., 202,208) by the wireless devices 104, 106 is randomized to reducecollisions. When second network activities are synchronized,randomization can be provided, for example, by adding a random backoffto the scheduled notification signal transmission.

FIG. 3 shows a block diagram of a wireless device 104 configured fornetwork arbitration based on channel access notification signals inaccordance with various embodiments. The wireless device 104 includesthe transceiver 112 configured for communication via the first networkand the transceiver 114 configured for transmission via the secondnetwork. The transceiver 112 is associated with a clock 302, and thetransceiver 114 is associated with a clock 304. The transceivers 112,114 are coupled to one or more antennas 306. In some embodiments, thetransceivers 112, 114 are coupled to one or more different antennas.

The wireless device 104 also includes an arbiter 308 coupled to thetransceivers 112, 114. The arbiter determines which of the transceivers112, 114 is allowed to access the transmission channel (e.g., allowed totransmit) at a given time. The arbiter 308 includes notification module310 that schedules transmission of a notification signal 202. Therandomize module 312 adjusts (i.e., randomizes) the scheduledtransmission time of a notification signal 202 to reduce collisions.

Transceiver 1 112 receives timing information transmitted by a timingsource on the first network (e.g., access point 102). The timinginformation is used to synchronize clock 302 to with other clocks in thefirst network. Clock 304 associated with transceiver 2 114 may besynchronized with clock 302 to provide synchronization of clocks in thesecond network.

The network 2 data source/sink 316 provides data to transceiver 2 114for transmission on the second network. When data is prepared fortransmission, the data source/sink 316 informs the arbiter 308. Thearbiter 308 schedules transmission of a notification signal 202 viatransceiver 1 112. The notification signal 202 specifies a time andduration for packet transmission or receipt on the second network.Following transmission of the notification signal 202, the arbitergrants exclusive channel access rights to transceiver 2 114 for the timeinterval specified in the notification signal 202.

When the specified time interval elapses, the arbiter 308 allowstransceiver 1 112 to transmit or receive.

Similarly, when a notification signal 208 is received by transceiver 1112, the arbiter 308 disables transceiver 1 112 from transmitting andmay enable transmission by transceiver 2 114 for the time intervalspecified in the notification signal 208. If the arbiter 308 hadpreviously scheduled transmission of a pending notification signal 202,the transmission is cancelled, if the duration specified in the receivedsignal is long enough to provide the pending activity on transceiver 2114, and another notification signal 202 transmission is scheduled for arandomized interval after the expiration of the time interval specifiedin the notification signal 208.

Various components of the wireless device 104, including at least someportions of the transceivers 112, 114, the clocks 302, 304, and thearbiter 308, can be implemented using a processor and softwareprogramming that causes the processor to perform the operationsdescribed herein. In particular, software programming can be used tocause a processor to provide synchronization of clocks 302, 304,generation and scheduling of notification signal transmission, andchannel access arbitration based on notification signals includingenabling transceiver 2 114 transmissions in response to a receivednotification signal. Suitable processors include, for example,general-purpose processors, digital signal processors, andmicrocontrollers. Processor architectures generally include executionunits (e.g., fixed point, floating point, integer, etc.), storage (e.g.,registers, memory, etc.), instruction decoding, peripherals (e.g.,interrupt controllers, timers, direct memory access controllers, etc.),input/output systems (e.g., serial ports, parallel ports, etc.) andvarious other components and sub-systems. Software programming can bestored in a computer readable medium. Exemplary computer readable mediainclude semiconductor memory, optical storage, and magnetic storage.

Some embodiments can implement the functionality described herein usingdedicated circuitry. Some embodiments may use a combination of dedicatedcircuitry and software executed on a processor. Selection of a hardwareor software/processor implementation of embodiments is a design choicebased on a variety of factors, such as cost and the ability toincorporate changed or additional functionality in the future.

FIG. 4 shows a flow diagram for a method of network arbitration thatsynchronizes activities on the second transceiver based on timingsignals received from the first transceiver and that controlstransmission based on channel access notification signals in accordancewith various embodiments. Though depicted sequentially as a matter ofconvenience, at least some of the actions shown can be performed in adifferent order and/or performed in parallel. Additionally, someembodiments may perform only some of the actions shown. In someembodiments, the operations of FIG. 4, as well as other operationsdescribed herein, can be implemented as instructions stored in acomputer readable medium and executed by a processor.

In block 402, a wireless device 104 including co-located networktransceivers 112, 114 each configured for operation on different andincompatible wireless networks is configured to wirelessly communicateby time multiplexed operation of the transceivers 112, 114. Transceiver1 112 receives timing information transmitted by a timing source in afirst wireless network. In some embodiments, the wireless device 104uses the timing information to synchronize a clock 302 in the wirelessdevice 104 to the timing source. Thus, each device in the first networkshares a common clock.

In block 404, the wireless device 104 synchronizes transceiver 2 114transactions to the clock 302. The synchronization may be accomplishedby synchronizing a clock 304 associated with transceiver 2 114 to theclock 302. With the synchronization of the clock 304, the wirelesstransaction activities of all wireless devices using the second networkare synchronized. In some embodiments, periodic transactions viatransceiver 2, 114 of a plurality of devices using the second networkmay by synchronized. Such synchronization may facilitate using a singlenotification signal to facilitate simultaneous second networktransactions by multiple devices.

In block 406, the wireless device 104 has data to transmit to a wirelessdevice 108 via the second network. To reserve communication channelaccess for transceiver 2 114, transmission of a notification signal 202via transceiver 1 112 is scheduled for a random time shortly before thetransaction via transceiver 2 is scheduled to begin. The notificationsignal 202 includes information defining a time duration during whichother wireless devices (e.g., access point 102, wireless device 106)that are associated via the first network are required to refrain fromtransmitting on the first network.

In block 408, the wireless device 104 checks for reception of anotification signal 208 transmitted by different wireless device in thefirst network. If a notification signal 208 has been received, and thetime duration specified by the notification signal is at least as greatas the time required for the scheduled transceiver 2 transaction, thenthe wireless device 104 disables transmission via transceiver 1 112 forthe duration specified in the notification signal 208, and enablestransceiver 2 114 to perform the scheduled transaction on the secondnetwork in block 412. A notification message 202 pending fortransmission in the wireless device 104 may be discarded based onreception of the notification signal 208.

If, in block 408, no notification message 208 has been received, then inblock 410, the wireless device 104 transmits the notification signal viatransceiver 1 112. Thereafter, transceiver 2 114 is enabled to performthe scheduled transaction on the second network in block 412.

The above discussion is meant to be illustrative of the principles andvarious embodiments of the present invention. Numerous variations andmodifications will become apparent to those skilled in the art once theabove disclosure is fully appreciated. It is intended that the followingclaims be interpreted to embrace all such variations and modifications.

What is claimed is:
 1. A wireless device, comprising: a first wirelesstransceiver and a second wireless transceiver, the first transceiverconfigured for operation with a first wireless network, and the secondtransceiver configured for operation with a second wireless network; andlogic that determines which of the first and second transceivers isenabled to transmit at a given time; wherein the logic causes the firsttransceiver to transmit a notification signal indicating a time periodduring which the second transceiver of the device will perform a firstwireless transaction and during which, based on receiving thenotification signal, a different wireless device performs a secondwireless transaction via the second wireless network withouttransmitting a notification signal.
 2. The wireless device of claim 1,wherein the first wireless network is incompatible with the secondwireless network.
 3. The wireless device of claim 1, wherein thewireless device randomizes transmission of the notification signal. 4.The wireless device of claim 1, wherein the logic discards a pendingnotification signal transmission when a notification signal is received.5. The wireless device of claim 4, wherein the logic schedulestransmission of a notification signal for a random time before awireless transaction via the second transceiver is scheduled to begins.6. The wireless device of claim 1, wherein the wireless device is amember of a first group, and a system comprises the first group and asecond group each group comprising a plurality of different wirelessdevices configured to communicate via the first and second wirelessnetworks, and the notification signal affects second networktransactions only of members of the first group.
 7. The wireless deviceof claim 1, wherein the first transceiver wirelessly receives a timingsignal and the logic synchronizes wireless transactions of the secondtransceiver to the timing signal.
 8. The wireless device of claim 7,wherein a clock used by the second transceiver is synchronized to thereceived timing signal and the second transceiver is granted wirelesstransaction rights at a predetermined period based on the clock.
 9. Thewireless device of claim 1, wherein the second transceiver is aBluetooth transceiver and the first transceiver is one of a wirelesslocal area network transceiver and a wireless wide area networktransceiver.
 10. A method, comprising: receiving, by a first wirelessdevice via a first transceiver configured for operation on a firstwireless network, a notification signal transmitted on the first networkby a second wireless device, the notification signal indicating a timeperiod during which the second wireless device will perform a wirelesstransaction on a second wireless network; enabling, based on receptionof the notification signal, a second transceiver of the first wirelessdevice to perform a different wireless transaction on the secondwireless network during the time period specified in the receivednotification signal; wherein the first wireless device performs thewireless transaction absent a corresponding notification signaltransmission by the first wireless device.
 11. The method of claim 10,further comprising abandoning a scheduled notification signaltransmission by the first wireless device based on reception of thenotification signal transmitted by the second wireless device.
 12. Themethod of claim 10, further comprising scheduling a notification signaltransmission by the first wireless device for a random time prior to ascheduled wireless transaction via the second transceiver.
 13. Themethod of claim 10, further comprising: receiving a timing signal viathe first transceiver; and synchronizing the timing of the transactionsvia the second transceiver based on the timing signal.
 14. The method ofclaim 13, further comprising determining transmission times for thesecond transceiver based on the timing signal.
 15. The method of claim9, further comprising grouping a first plurality of wireless devices andgrouping a second plurality of wireless devices, each grouping ofdevices configured for operation on the first and second networks;wherein wireless transactions via the second transceiver of devices ineach grouping are affected only by a notification signal transmitted bya device in the same grouping.
 16. A wireless device, comprising: afirst wireless transceiver configured for communication via a firstwireless network; a second wireless transceiver configured forcommunication via a second wireless network; and an arbiter thatcontrols which of the first and second transceivers is enabled totransmit at a given time; wherein the arbiter schedules wirelesstransactions via the second transceiver based on timing signalswirelessly received via the first transceiver.
 17. The wireless deviceof claim 16, wherein the arbiter schedules transmission of anotification signal indicative of an upcoming transaction using thesecond transceiver to occur at a random time prior to the upcomingtransaction.
 18. The wireless device of claim 16, wherein the secondtransceiver is configured to perform transactions via the second networkin synchronization with a second transceiver of a different wirelessdevice.
 19. The wireless device of claim 16, wherein the arbiterdiscards a pending notification signal transmission and schedules a newnotification signal transmission based on wirelessly receiving anotification signal transmitted via the first network by a differentwireless device.
 20. The wireless device of claim 16, wherein thearbiter enables the second transceiver to perform a wireless transactionduring a given time interval based on a notification signal wirelesslyreceived by the first transceiver, the notification signal indicatingthat a different wireless device transmitting the notification signalwill perform a wireless transaction on the second wireless networkduring the given time interval; and wherein communication via the firstnetwork conflicts with communication via the second network.